This invention relates to magnetic data storage and retrieval apparatus, and more particularly to processes for improving the surface properties of magnetic discs or other media, and of sliders for magnetic reading and recording transducers.
The employment of selected surface coatings and other treatments is a well known technique for enhancing the useful life and reliability of magnetic media and sliders of magnetic data reading and recording heads. Magnetic discs and sliders are subject to wear along their interfaces or areas of mutual surface engagement as they are moved relative to one another. Even in disc drives employing "flying" heads which normally are separated from the disc by a thin air foil, the surface contact during repeated starts and stops of disc rotation can cause substantial wear to the interfacing surfaces, and eventually can lead to a head crash.
Accordingly, surfaces of sliders and discs frequently are treated to increase their toughness and strength, and to reduce friction. For example, in U.S. Pat. No. 4,251,297 (Kawabata) a boronized layer is formed on the surface portion of a slider disposed to contact the magnetic recording medium. U.S. Pat. No. 4,631,613 (French) discloses a plasma process for improving the saturization magnetization of the transducer. In particular, a gap spacer material and a pole piece are deposited using an Alfesil target along with either argon or nitrogen gas.
In connection with a device in which the slider is normally in contact with a magnetic tape or disc, a technique to improve the slideability between a disc and slider is disclosed in U.S. Pat. No. 4,649,488 (Nakajima). The sliding surface of a head is coated with a zirconium oxide or other material having a high coefficient of thermal expansion, in particular high enough to carbonize the binder of the recording medium.
U.S. Pat. No. 4,619,861 (Nakayama) discloses a plasma polymerization technique for coating the particles which make up magnetic powders. The technique is said to improve the disperseability, squareness ratio and dusting of the magnetic powders. Another known approach is to provide a passivation layer of sputtered carbon over the magnetic media or recording layer of a disc, both to protect the media layer against corrosion and to improve surface lubricity. The carbon overcoat is quite thin, typically in the range of 300 to 400 Angstroms, and as formed, includes micro-pores and sometimes "pinholes" exposing the media layer. Another problem encountered with the carbon overcoat is a build-up of debris, principally carbon particles, on the disc surface. The slider, due to high surface energy, tends to pick up this debris, leading ultimately to a head crash.
Therefore, it is an object of the present invention to provide a treatment for ceramic materials to reduce surface friction and improve the hardness and toughness of the surfaces of such materials.
Another object of the invention is to provide a slider with an interfacing surface of improved toughness, hardness and lubricating characteristics, and reduced surface energy.
Another object of the invention is to provide a process for surface treatment of head sliders for use with magnetic media, to improve the surface properties of such sliders.
Yet another object is to provide sliders having reduced friction at the interface with magnetic media, thereby to reduce noise due to friction and increase signal quality.